Although many studies of chronic protein deprivation have been carried out, very little has been done with regards to the effect of acute short term periods of protein deprivation on the ability of a lymphohematopoietic system injured by systemic cancer therapy to repair and restore itself. Preliminary studies by us of the ability of transplanted bone marrow to repopulate a lethally irradiated mouse have clearly demonstrated that in the presence of no protein intake, there is marked prolongation and suppression of full engraftment of that transplanted marrow. The studies proposed herein will examine the quantitative effect of graded doses of dietary protein to restore normal repopulation kinetics of transplanted bone marrow. Studies will also be carried out to examine quantitatively the effect of graded amounts of dietary protein on the ability of autologous residual bone marrow CFUs and CFUc to restore and repopulate the mouse after sublethal systemic chemotherapy and irradiation. Using the adoptive transfer system, we will determine quantitatively the effect of those same protein deficient diets on the ability of syngeneic immunocompetent cells to recover. These studies will be extended to the study of the replicative ability of CFUs, CFUc, and their progeny from murine bone marrow cultured in diffusion chambers implanted into mice mantained for a short period of time on graded protein diets. Marrow from normal humans and patients with leukemia in varying states of remission and relapse will be grown in diffusion chambers implanted into chemotherapy and/or radiation treated mice. These mice will be subjected to dietary deprivation post chamber implantation. At each of several times during culture, the effect of this deprivation on the chamber total and differential cell count, as well as the content of CFUc will be determined.